Record creation date in Metastore

To make time-based rotation logic easier, add a creation timestamp in Metastore. Ensure that backwards compatibility is maintained. See about building time-based rotation into request logic so consumers get it automatically.

首先定位 Metastore 和请求逻辑，然后跟踪现有元数据的存储和读取方式。定义如何在不破坏旧数据的情况下添加创建时间戳，并确认基于时间的轮换信息会自动传递给消费者。

由索引模型根据 Issue 内容生成。